/*
 * Copyright 2007 Matt Jensen
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 */
package org.jtell;

/**
 * <p>
 * <code>EventMetadataSource</code> defines the public interface to an event metadata source. Instances examine event
 * objects and extract their attribute values.
 * </p>
 */
public interface EventMetadataSource
{
    /**
     * <p>
     * Get metadata for an event object. If an implementation cannot provide metadata for an event, it should return
     * <code>null</code>, which will cause the event to be passed to the next configured metadata source for
     * examination.
     * </p>
     *
     * @param event the event object.
     * @return {@link EventMetadata} instance or <code>null</code> if metadata cannot be supplied by this instance.
     */
    EventMetadata getEventMetadata(Object event);
}
